* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* em和i斜体的文字不倾斜 */
em,
i {
    font-style: none;
}

li {
    list-style: none
}
a{
    text-decoration: none;
    color:#333;
}
button,input{
    outline:none;
    border: 0;
}
a{
    font-size: 12px;
}